X-ray computed tomography, also computed tomography (CT), is a medical imaging method employing tomography created by computer processing. Digital geometry processing is used to generate a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. CT imaging produces a volume of data that can be manipulated, through a process known as “windowing”, in order to demonstrate various bodily structures based on their ability to attenuate the X-ray beam. Although historically the images generated were in the axial or transverse plane, perpendicular to the long axis of the body, modern scanners allow this volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures. Although most common in medicine, CT is also used in other fields, such as nondestructive materials testing and imaging interior portions archaeological relics. Usage of CT has increased dramatically over the last two decades in many countries. An estimated seventy-two million scans were performed in the United States in 2007.